Pages

Monday, October 26, 2009

More and More Boys Born With Deformed Genitals -- What's to Blame?

I'm pretty sure I have ranted here before on the evils of xenoestrogens, those synthetic estrogens produced in the petroleum products, plastics, pesticides, cleansers, air fresheners, auto exhaust, and a million other sources. These things screw up the hormonal balance of the body (endocrine system) and seem to be most dangerous during pregnancy, especially for male fetuses.

Xenoestrogens have been implicated in a variety of medical problems, and while there has been little hard evidence of damage, the potential for adverse effects is considered real.[2]

Foremost is the concern that xenoestrogens as false messengers disrupt the process of reproduction. Xenoestrogens have an effect similar to that of naturally produced estrogen and can increase growth of the endometrium, so treatments for endometriosis include avoidance of products which contain them. Likewise, they are avoided in order to prevent the onset or aggravation of adenomyosis. Studies have implicated observations of disturbances in wildlife with estrogenic exposure; for example, in some areas of the southeast United States, up to 90% of fish were found to be intersex.[3] Reproductive issues which are of concerns in humans are fetal exposure (perhaps leading to hypospadias) and decreased reproductive ability in men (i.e. decrease in sperm numbers).

Another issue is the potential effect of xenoestrogens on oncogenes, specifically in relation to breast cancer. Some scientists doubt that xenoestrogens have any significant biological effect, in the concentrations found in the environment.[4] However, there is significant proof in a variety of recent studies to indicate that xenoestrogens are a serious factor in breast cancer occurrence [5][6][7][8][9][10][11][12]

Even very low levels of a xenoestrogen, in this case Bisphenol A, could affect fetal neural signalling more than higher levels, indicating that classical models where dose equals response may not be applicable in susceptible tissue.[13] As this study involved intra-cerebellar injections, its relevance to environmental exposures is unclear.

Believers that environmental estrogen disruption is a major health hazard are opposed by detractors who argue that observed effects are spurious and inconsistent, or that the quantities of the agents are too low to have any effect.[14] A 1997 survey of scientists in fields pertinent to evaluating estrogens found that 13 percent regarded the health threats from xenoestrogens as "major," 62 percent as "minor" or "none," and 25 percent were unsure. [15]

The incidence of falling sperm counts in males may be due to increased oestrogen exposure in utero.[16] Sharpe in a 2005 review indicated that external estrogenic substances are too weak in their cumulative effects to alter male reproductive functioning, but indicates that the situation appears to be more complex as external chemicals may affect the internal testosterone-estrogen balance.[17]

This new article from AlterNet suggests that the fears we have had about the impact of xenoestrogens is becoming a very real problem for children, especially boys, who are most vulnerable to the effects of these chemicals.

Scientists are casting a wide net in search of chemicals seen as likely suspects in feminization and reproductive anomalies being spotted worldwide.

The term "endocrine disruptor" had not been coined when Rachel Carson was alive, but she was onto them.

Carson's groundbreaking 1962 book on the dangers of synthetic pesticides, Silent Spring, was prescient in many ways. She wrote about what she termed "insecticide storage:" "There are indications that these chemicals lodge in tissues concerned with the manufacture of germ cells as well as in the cells themselves. Accumulations of insecticides have been discovered in the sex organs of a variety of birds and mammals. ... Probably as an effect of such storage in the sex organs, atrophy of the testes has been observed in experimental mammals. Young rats exposed to methoxychlor had extraordinarily small testes."

Al Gore, who wrote in the forward to zoologist Theo Colborn's book on endocrine-disrupting compounds, Our Stolen Future, noted that Carson warned in one of her last speeches: "We are subjecting whole populations to exposure to chemicals, which animal experiments have proved to be extremely poisonous and, in many cases, cumulative in their effects. These exposures now begin at or before birth and — unless we change our methods — will continue through the lifetime of those now living. No one knows what the results will be because we have no previous experience to guide us."

Endocrine Disruptors

Earlier this month Miller-McCune discussed the observations and practical science of a woman, Judy Hoy, sounding an alarm in western Montana. A wildlife rehabilitator, Hoy has documented malformations of genitalia of local white-tailed deer over a 13-year period in the Bitterroot Valley. She suspects the changes are caused by endocrine-disrupting compounds (or EDCs), possibly from pesticides applied to potato fields just over the border in Idaho.

Montana officials so far have discounted her hypothesis, but scientific research around the world has made similar findings - undescended and abnormally small penises and testicles, low sperm counts, genitals placed forward on the body, confused gender - in test animals and in wild populations of birds, reptiles and wildlife.

What causes these changes remains contentious. Many scientists and public health advocates point to pesticides and other environmental pollutants while others, including industry, some government agencies and more scientists, say more study is needed.

While debating mutations in deer populations is one thing, finding those changes in boy babies takes the discussion to a new level.

Results of a study released in May 2009 by the British nongovernmental organization CHEMTrust show:

• as many as 1 in 17 boys in the United Kingdom have undescended testicles, a congenital birth defect;

• malformation of the penis (where the opening is not at the end) has increased in recent decades in several European countries, the United States, Australia and China;

• U.K. and French data show a decline in sperm count in young men as compared to their fathers; in some European countries, 1 in 5 young men has sperm counts so low that it is likely to affect their ability to father a child; and

• Testicular cancer is the most common cancer of young men, doubling in incidence in many Western countries every 25 years over the past 60 years.

The author of the report, Richard Sharpe, of the U.K.'s Medical Research Council wrote that many scientists are tying a lack of testosterone at critical times of fetal development to "testicular dysgenesis syndrome," encompassing defects of boys' genitals, low sperm counts and testicular cancer. He sees a link between hormone-disrupting chemicals and TDS, saying animal studies "have established beyond a doubt that certain hormone-disrupting chemicals, in particular testosterone-disrupting chemicals, can cause TDS-like disorders."

His meta-study might be one that Rick Becker, senior toxicologist with the American Chemical Council, would caution against. Becker asks that people not leap to conclusions after reading individual reports, but look to the World Health Organization for its synthesis of studies. However, the most recent WHO report on EDCs, "Global Assessment of the State of the Science of Endocrine Disruptors," was published in 2002.

After a lengthy review of scientific findings on the effects of the chemicals on human reproduction, the WHO report makes no firm conclusions. The authors note in a conclusions and recommendations section that "exposure data are very limited, if available at all, and in many studies exposure has only been inferred and not actually measured." Another problem cited is that sample sizes are often small, resulting in a finding that "the currently available human data are inadequate to support a conclusion that human reproductive health has been adversely affected by exposure to EDCs."

Still, the section concludes, "Despite these drawbacks, the biological plausibility of possible damage to human reproduction from exposure to EDCs seems strong when viewed against 1) the background of known influences of endogenous and exogenous hormones on many of the processes involved, and 2) the evidence of adverse reproductive outcomes in wildlife and laboratory animals exposed to EDCs."

Many studies on EDCs have been published since 2002. Sharpe's paper references 159 papers and information sources, 101 written after the WHO report was prepared.

In June, the Endocrine Society, a nearly century-old international association of endocrinologists, issued a statement in which its position was clear. In a 50-page paper, the first scientific statement issued by the society, authors wrote: "We present evidence that endocrine disruptors have effects on male and female reproduction, breast development and cancer, prostrate cancer, neuroendocrinology, thyroid, metabolism and obesity and cardiovascular endocrinology. Results from animal models, human clinical observations and epidemiology studies converge to implicate EDCs as a significant concern to public health." (Breast Cancer UK recently produced a video linking EDCs to breast cancer that can be seen on YouTube.)

There has been controversy regarding various studies of sperm count decreases in men; data has varied with study and locale of men tested. One U.S. scientist known for her work in reproductive epidemiology, Shanna Swan, authored a report that appeared in Environmental Health Perspectives in 1997 that analyzed sperm-count studies and concluded that "further analysis of these studies supports a significant decline in sperm density in the United States and Europe but not in non-Western countries." She found the studies showed that there are "large inter-area differences in sperm density."

Swan has been studying the effects of environmental pollutants for nearly 30 years, including the effects of contaminants on various aspects of human reproduction (including fetal loss, fertility, low birth weight, birth defects, semen quality and sex hormones). She began in 1981 by studying the possible contamination of a public water supply by a toxic release from a semiconductor plant for the California Department of Health Services in 1981. Today, she is associate chair for research in the Department of Obstetrics and Gynecology at the University of Rochester School of Medicine and Dentistry, and director of the Center for Reproductive Epidemiology.

In 2005, she and other colleagues published a paper in Environmental Health Perspectives that was the first research to link human male birth defects to a known EDC, phthalates. It showed that boys born to mothers exposed to phthalates during pregnancy were likely to have smaller genitals and incomplete testicular descent. Previous studies had shown similar outcomes in rodents.

The federally financed study used levels of phthalates that are found in one-quarter of the female population in the country. Researchers also found that in the 25 percent of mothers with the highest levels of phthalate exposure, the odds were 10 times higher that their sons would have a shorter-than-expected distance between the anus and the base of the penis (the anogenital distance), which is an indicator of impacts on the reproductive system.

Those involved in the discussion of EDCs agree more studies are needed - to conclude the chemical compounds are as dangerous as some believe or to put the controversy to rest by discounting the role they play in the endocrine system.

Research of potential EDC effects is not particularly easy for many different reasons. Wildlife, obviously, are difficult to study and research, and studies of EDCs are particularly difficult to conduct on human populations (e.g., pregnant women). Sharpe noted in his report that it is not easy to find mothers who haven't been exposed to chemicals, making it difficult to find "controls" for experiments.